The present invention relates to a test socket for testing a bare integrated circuit. More specifically, the present invention is directed to a test socket for testing a known-good die using a shape memory alloy as the contacts.
Integrated circuit technology has progressed so that it is possible to mount a bare integrated circuit directly to a circuit board without enclosing it in a package having solder pins for mounting. One method of mounting a bare integrated circuit is called flip chip, which is commonly known in the art. In using the flip chip technique, the integrated circuit is tested before installation directly on the circuit board.
The testing of a known-good die is difficult because of the size of the package and the potential for varying heights in the bond pads. Making and maintaining a reliable electrical connection throughout the testing process is critical. Known test fixtures are also limited in durability.
One type of testing apparatus for a component having solder pins is described is U.S. Pat. No. 4,950,173. The apparatus uses a shape memory alloy having an opening for insertion of a component lead through the alloy. The component leads are gripped by the alloy and the circuit is then tested. The apparatus is also believed to be expensive since durability is believed to be limited to a relatively small number of testing cycles.
One problem with applying a component lead-gripping system to a known-good die which does not have solder pins is that the solder pads on a known good die are not very large. Consequently, there is little surface area for which to apply a gripping force to make a solid electrical contact.
It would therefore be desirable to provide a method and apparatus for reliably testing known-good dice which is also durable.